(Independent/amaq) -- ISIS has released a video through its Amaq news agency which purports to show the Tehran terror attack from inside the Iranian parliament building.

Apparently filmed by the assailants, the short clip shows the injured or dead body of a man in business attire lying on the floor of an office room as a man with an assault rifle walks past.

The fighters can be heard shouting in Arabic, rather than Farsi, as gunshots ring out and alarms go off in the background. "Oh God, thank you... Do you think we will leave? No! We will remain, God willing," one of them says.

Tehran was hit by twin terror attacks on Wednesday morning involving gunmen and suicide bombers at both parliament and the tomb of Ayatollah Ruhollah Khomeini in the south of the city.

Iran's state news agency has put the combined death toll at 12, and another 30 people are reported to have been injured.